Interchangeable crown.



H. A. MARX. INTERCHANGEABLE CROWN. APPUCATIDN FILED FEB. 10. 1915.

Patented Mar.

111B COLUMBIA mm" 0.. WMHINGTON, D. C.

HARRY A. MARX, OF PORT HURON, MICHIGAN.

INTERCI-IANGEABLE CROW'N.

Specification of Letters Patent.

Patented Ma. a, was.

Application filed February 10, 1915. Serial No. 7,292.

To all whom it may concern:

Be it known that I, HARRY A. Manx, a citizen of the United States, and aresident of Port Huron, county of St. Clair, Statei one object thereofis to provide a porcelain or other crown of such construction that whilebeing applicable to a suitably formed backing so as to be rigidly heldfrom movement, it is structurally strong and its connection with saidbacking is of such a nature that it is not likely to become loosened orbreak.

I further desire to provide a crown or artificial tooth which shall beprovided with a transverse groove and an adjacent plane surface both ofwhich. are ground after baking to standard dimensions in order that saidcrown may fit a standard backing plate and be interchangeable with otherteeth of the same form but of different coloring.

Another object of the invention is to provide a novel form of crown andbacking therefor which shall not only be sightly but shall be of astrong construction and easily assembled and applied to dental bridgework.

- These objects and other advantageous ends I secure as hereinafter setforth, reference being had to the accompanying drawings in which Figure1 is a perspective view of a. crown or artificial tooth constructedaccording to my invention; Fig. 2 is a perspective view of the preferredform of backing employed with the tooth shown in Fig. 1; Figs. 3 and 4are respectively a, vertical section and a plan of the tooth shown inFig. 1, and Figs. 5 and 6 are respectively a perspective view and avertical section of another form of tooth showing my invention asapplied thereto. I

In Figs. 1, 3 and 4 of the above drawings, 1 represents an artificialtooth of porcelain or other suitable material, whose biting surface 2and whose front surface 3 are formed to resemble as closely as possiblethe same portions of a natural tooth, while that portion 4 of the backsurface of the tooth, which intersects the biting surface, likewise hasa natural form. The tooth or crown is also formed with a plane inner orlingual surface 5 extending from the rear surface at to a surface 6whose edge distant from the biting surface intersects the front surface3 of the crown. At or adjacent the line of intersection of the twosurfaces 5 and 6, I provide a groove 7 extending transversely of thetooth in the thickest portion thereof and having a rectangular section,its arrangement being such that its bottom is substantially parallelwith the plane of the rectangular surface 5.

According to my invention the surface 5 and the walls of the groove 7are accurately ground to standard dimensions after the tooth is baked sothat any tooth will accurately fit a suitably formed backing such asthat shown in Fig. 2. This backing consists of a flat metal plate 8preferably of uniform thickness having along one edge a projecting rib 9of rectangular section of such dimensions as to closely fit thetransverse groove 7 of any of the teeth constructed according to myinvention, at the same time that the flat body portion 8 likewiseaccurately fits upon the base of the lingual surface 5.

The outline of the plate 8 may be made to conform more or less closelyto the outline of the surface 5 and a post 10, preferably projectingfrom the central portion of the rib 9, is designed to enter a suitablyplaced hole 11 in the tooth or crown 1. It is to be noted that thegroove 7 is so placed that it extends transversely of what is thethickest and therefore the strongest part of the crown, and that thehole for the post 10 likewise extends at right angles to the line ofthis groove into the thick central part of the tooth.

Whilein Figs. 1, 3 and 4 I have shown a molar tooth or crown constructedaccording to my invention, I have illustrated in Figs. 5 and 6 anincisor tooth formed with the plane lingual surface 5 and a transverselyextending groove 7 having its bottom parallel with said surface. In thiscase a plane surface 12 extends from the front surface of the tooth,back to the front wall of the groove 7 at a more or less acute angle tothe plane of the surface 5 In any case it is to be noted that the base 5of the lingual surface, the walls of the slot 7 and the post receivinghole 11 are ground to standard sizes so that any tooth will accuratelyfit the standard backing, the post hole 11 preferably projectingforwardly into the front portion of the body of the tooth in a lineinclined to the, plane The combination of a substantially flat andtransversely continuous backing plate, havlng an ofl'set transverse ribof substantially rectangular cross section; a crown having 'a-contlnuousplane surface for the receptlon of the corresponding part of sald plateand formed with a transverse groove of substantially rectangular sectionfor the reception of the rib on the plate, said plate having a postextending from said rib into the crown. v

In testimony whereof, I have signed my name to this specification, inthe presence of two subscribing witnesses.

HARRY A. MARX.

lVitnesses: V Y

WILLIAM E. BRADLEY, WM. A. BARR.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. c.

